1. Field of the Invention
The present invention relates generally to an image-capturing apparatus such as a digital camera, and more particularly to an image-capturing apparatus which is suitable for use in photographing paper sheets such as paper documents and business cards, and to an image processing method and a program product for use in the image-capturing apparatus.
2. Description of the Related Art
In a case where a paper sheet such as a paper document or a business card is a photographic subject, the paper sheet has to be placed on the desk or the like and the photographer has to photograph the paper sheet with a camera situated downward from just above. As a result, the paper sheet may possibly be photographed in an oblique direction. Conventionally, to cope with this problem, contour information of the photographic subject is extracted from the image that is captured in the oblique direction, and a distortion of the captured image is corrected on the basis of the contour information (see, e.g. Jpn. Pat. Appln. KOKAI Publication No. 2005-115711).
However, since the paper sheet that is the photographic subject is photographed in the state in which the paper sheet is placed on the desk or the like, the edge portion of the desk, for example, becomes an obstacle to the photographing and the contour information of only the paper sheet that is the subject cannot correctly be extracted. If the contour information is not extracted, the distortion of the acquired image cannot be corrected. It is thus required to carefully photograph the paper sheet by placing it at the center of the desk so as to prevent the edge portion of the desk, for instance, from entering the range of photographing.
In addition, in a case where a plurality of paper sheets are photographed and the captured images are stored, if the paper sheets are overlaid and photographed, the contour of the previously photographed paper sheet becomes an obstacle and the contour of the newly placed paper sheet cannot exactly be extracted, and the captured image cannot be corrected. As a result, a timing-consuming work of, for example, replacing the paper sheets one by one is necessary.